A forming press for forming a sheet-like blank composed of metal is known from the prior art according to DE 10 2012 106 299 A1. It provides in particular a pressure-tight housing, wherein two frame parts are disposed in the housing, wherein the one upper frame part is movable toward the other bottom frame part. The one upper frame part comprises a punch, which is movable in a cylindrical chamber of the frame part, and which features a positive engraving, whereas a die with a correspondingly complementary negative engraving is disposed on the other bottom frame part. The method for forming the sheet-like blank of metal consists in first carrying out a gas-based forming of the blank, and then, in a second step, i.e. when the forming has already substantially taken place, in carrying out a final mechanical forming sheet-like blank in those sections of the die that are characterized by small radiuses. Indeed, according to the teachings of the prior art, gas pressure forming allows achieving proportionately high degrees of deformation relatively simply and quickly, whereas the forming of small radiuses at equally high degrees of deformation requires exerting a disproportionately high pressure on the blank, which makes such a one-step method uneconomical when small radiuses need to be deformed. According to the prior art, the forming of the sheet-like metal blank is carried out by the stroke of the punch, respectively of the frame parts relative to one another, by generating gas pressure. Furthermore, this citation also teaches providing higher pressures for the forming process by increasing the temperature. However, it also teaches to load the pressure chamber, after it has been sealed but before the start of the actual compression stroke, with the gas pressure that has been generated in the previous press stroke, for reducing the compression path and/or for increasing the final pressure. The gas under pressure can be temporarily stored in a pressure vessel. In short, this means that the teaching of the prior art amounts to using the pressure generated by the displacement of the punch, respectively a pressure generated by the displacement of the two frame parts, for the forming process, wherein pressurized air, temporarily stored in a pressure vessel before the actual forming process, is used, as necessary, for increasing the pressure in the chamber above the punch.
Generating the required pressure using gas, as a pressurizing medium, requires considerable traveling distances, which means that the cycle times become relatively long. Since not only the punch is to be used for generating the pressure, and the two frame parts also serve to increase the pressure in the punch chamber, it is necessary to hermetically seal the frame parts of the press, i.e. the upper frame part and the bottom frame part, from the environment. As can be seen in the drawings of DE 10 2012 106 299 A1, a separate housing is provided to this end. It makes not doubt that this requires a considerable constructive and manufacturing effort, which makes such a device, and here more specifically the tool part, relatively expensive.
Therefore, the problem underlying the invention consists in providing a more economical solution for forming a sheet-like blank composed of metal.